Waste water treatement processes typically include a step in which gas is contacted to the waste water being treated. It is known to use unilaterally open diffuser pipes for elastomeric diffuser sleeves which are perforated for air to pass through to introduce air in the form of fine bubbles into waste water. See, e.g., U.S. Pat. No. 4,165,286 to Schreiber. In a typical device of this type, the diffuser sleeves are mounted on the diffuser pipes by means of hose clips. The diffuser pipes are closed by a solid wall on their sides opposite to the open ends. A threaded nut or sleeve is inserted inside the wall, into which a tie rod can be screwed via a bore. A tie rod connects two coaxially arranged carrier pipes with the air pipe at a right angle, with the tie rod extending through the air supply pipe. Such an arrangement is disclosed, for example, in DE-OS 34 18 548. See also U.S. Pat. No. 4,060,486 to Schreiber.
While in the above-described design the tie rod only extends into the solid breechlock mechanism parts of the diffuser pipes, it is common practice in other known aeration systems to extend the tie rod through the entire length of the nonfloodable diffuser pipes. The ends of the tie rod are provided with a thread and extend through the closing walls on the front side of the outer ends of the diffuser pipe. With the aid of nuts and sealing rings the diffuser pipes are pressed, impermeably to gas, with their inner open ends against a gas supply pipe.
Both of these designs, particularly the design shown in DE-OS 34 18 548, have a common disadvantage: they are costly to manufacture. Moreover, the mounting of two nonfloodable diffuser pipes with the assistance of a continuous tie rod it not a construction suitable for assembly and disassembly by one person because of the large dimensions and the numerous component parts involved. Of late, diffuser pipes have been constructed of plastic, but the buoyancy of such pipes requires special modifications to the apparatus to maintain the apparatus submerged. Accordingly, objects of the present invention are to provide an aerating apparatus which is low in buoyancy and can be assembled by one person from simple, commerically available and inexpensive parts.